It's not easy hunting frogs. For starters, there aren't many frogs left.

If you want to find a frog, you're best off in the flatlands of Madagascar, or maybe Papau New Guinea. But everywhere else? They've pretty much croaked.

"It's grim," said David Wake, an integrative biology professor at UC Berkeley and an expert on amphibians. "We actually have quite a few species, but the problem is, they're almost all in trouble."

Frogs across the globe, from the creeks of the Bay Area to the rain forests of Panama, are diminishing rapidly. About 50 percent of amphibian species worldwide are threatened or endangered, a higher number than any other vertebrate. Where frogs once happily hopped in backyards, ponds and streams, those places are now ribbit-less.

But the best hope for the slimy bug-eaters may lie in the Bay Area, where an increasing number of frog experts are pioneering research, education and captive breeding programs. The latest entry is Save the Frogs, the world's only nonprofit dedicated solely to saving amphibians, which recently opened its headquarters and a gift shop in Berkeley.

"I fell in love with frogs, and I realized that the greatest threat to frogs is people's lack of awareness," said Kerry Kriger, an environmental biologist who founded Save the Frogs six years ago. "I think when we protect frogs, we can protect the whole environment."

That's because frogs are a critical link in the food chain, he said. They eat huge quantities of bugs, especially mosquitoes, and are a favorite snack for a host of predators in creeks, ponds, forests and wetlands.

Kriger and his crew visit schools, work on legislation to ban pesticides, persuade restaurants not to serve frog legs, and encourage people to build frog ponds. They're working with Assemblyman V. Manuel Pérez, D-Coachella (Riverside County), to declare the endangered red-legged frog - made famous in Mark Twain's tale "The Celebrated Jumping Frog of Calaveras County" - as the official state amphibian.

Restaurants on board

Gary Danko, the high-end San Francisco restaurant, is among the establishments that have stopped serving frog's legs. Chez Panisse in Berkeley hasn't served frog legs in years.

But Save the Frogs most important work is overseas, where environmental degradation in developing countries poses some of the biggest threats to amphibians. Save the Frogs has staff in Ghana and Bangladesh, and has worked with governments, timber companies, universities and schoolchildren in Tanzania, Nepal, Colombia, Mexico and other countries.

Frogs began declining in the 1980s because of habitat loss and a host of pathogens, namely the chytrid fungus. In the past 35 years, almost 200 species of amphibians have become extinct, and hundreds more are threatened or endangered.

In California, 17 of about 67 amphibian species are threatened or endangered. Others appear to be in serious decline, but data are incomplete, Kriger said.

Other species at risk

No one's quite sure what caused the spread of chytrid, although it's probably linked to climate change and habitat destruction, Wake said. Other factors, such as pesticides and invasive species, exacerbate matters for a class of animals that's already weakened by disease.

"As we press further and further against nature and into the last wild places, we're seeing pathogens released," Wake said. "But amphibians generally are very tough organisms. They've been around a long time. That they've been so hard hit, I think, came as a great surprise."

Many scientists believe the amphibian die-off is a harbinger for other species, including Homo sapiens, as climate change and environmental destruction accelerates. But they also believe that saving the frogs could teach us how to save ourselves.

In the Bay Area, Professors Tyrone Hayes at UC Berkeley and Vance Vredenburg at San Francisco State have led the way in amphibian research, especially in pesticide and chytrid studies.

Wake's website, www.amphibiaweb.org, is a global clearinghouse for amphibian research, and the Oakland Zoo, California Academy of Sciences and San Francisco Zoo all participate in captive breeding programs for endangered frogs and toads.

Public involvement

Plus, there's no shortage of public interest in the Bay Area. On a recent frog-hunting foray into the Berkeley hills last week, dozens of passersby stopped to chat with Kriger and his staff about all things slimy. Sadly, the hour-long hunt yielded no frogs but plenty of salamanders. Newts and salamanders are also in decline, but not as seriously as frogs.

Gary Helfand, a designer from Berkeley who was hiking along Strawberry Creek, was especially interested.

"Frogs might be little, but when one little piece goes ... we don't know what role they play, how it's all connected," he said. "Frogs are as important as any species."

Such comments hearten Kriger, who believes that with enough public help, frogs can indeed be saved.

"As long as there are still frogs to save, I know we'll try to save them," he said. "Am I hopeful? Yeah. I know we can do it."

How the public can contribute

-- Don't use pesticides.

-- Build a frog pond in your backyard.

-- Don't eat frog's legs.

-- Don't buy wild-caught frogs as pets.

-- Drive slowly on wet nights.

-- Be eco-friendly in general: Recycle, save water, use less plastic, buy organic and educate yourself on environmental issues.